Re: UMTS For the U.S.?

I just got my nokia e51 and have realized that I cannot access the AT&T UMTS (3G) network. I called a usa nokia flagship store and was told that although this phone had UMTS 850 capability, it is not compatible with the one that AT&T uses- specifically this phone is compatible with Australia's UMTS network? If anyone else know any information please let me know.